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lumen

lu·men

lumen

pronunciation:
lu mn
features:
Word Parts
part of speech: noun
inflections: lumens, lumina
definition 1: a unit of measure of the flow of light, equal to the flow from a light source of one-candle strength, measured on a unit surface at a unit distance. (abbr.: lm)
definition 2: a hollow space, as in the bore of a hollow needle or in a bodily duct or tract.
Word Parts
The word lumen contains the following part:
luc, lum Latin root that means light; shine
synonyms:
phot, photo